The present invention relates to catalysts comprising (i) ZSM-5 or ZSM-11, (ii) gallium and (iii) thorium and to aromatization reactions conducted therewith.
The Chester et al U.S. Pat. No. 4,350,835 describes a process for converting ethane to liquid aromatics by contacting the ethane with a zeolite catalyst such as ZSM-5 having incorporated therein a minor amount of gallium.
The Davies et al U.S. Pat. No. 4,175,057 describes a process for producing aromatics by contacting a C.sub.3 -C.sub.8 hydrocarbon with a gallium catalyst supported on an aluminosilicate in which the ratio of silica to alumina is between 20:1 and 70:1.
The Bulford et al U.S. Pat. No. 4,157,356 describes a process for producing aromatic hydrocarbons by contacting a C.sub.3 -C.sub.8 hydrocarbon with a gallium catalyst on a silica support which has a surface area greater than 500 m.sup.2 /g and a pore volume less than 0.8 ml/g.
The Chu U.S. Pat. No. 4,276,437 describes a zeolite catalyst such as ZSM-5 having been modified by treatment with a compound of gallium to deposit thereon a minor proportion of this element on the zeolite. Also, the Chu U.S. Pat. No. 4,302,622 describes a similarly modified zeolite catalyst, wherein the gallium modifier is replaced by a Group IIIA element modifier. The catalysts of these Chu patents are described as being capable of converting aromatic compounds to dialkylbenzene compounds rich in the para-isomer.
The entire disclosures of the above-mentioned U.S. Patents are expressly incorporated herein by reference.